Membrane stack and air humidifier

Abstract

The invention relates to a membrane stack for an air humidifier of a fuel cell for humidifying a dry supply air flow of the fuel cell with a moist exhaust air flow of the fuel cell.SOLUTION: The membrane stack (9) is of cuboid design and has a stacking direction (S) and four stack planes transversely with respect to the stacking direction, A height direction (Z) extending parallel to the stacking direction; A longitudinal direction (X) running perpendicular to the height direction and a transverse direction (Y) running perpendicular to the height direction and perpendicular to the longitudinal direction, wherein the four stack planes form a charge air inlet and a charge air outlet (ZA) spaced apart from one another in the longitudinal direction and an exhaust air inlet (AE) and an exhaust air outlet (AA) spaced apart from one another in the transverse direction, wherein the membrane stack has a plurality of membranes (11), which are permeable to moisture and impermeable to air.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a membrane stack for a fuel cell air humidifier for humidifying a dry inlet air stream of a fuel cell with a humid exhaust air stream of the fuel cell according to the preamble of claim 1 .

[0002] German Patent Application No. 102021204247 discloses an air humidifier with a membrane stack as described above, which membrane stack has a rectangular parallelepiped configuration and has a stacking direction and four stack surfaces transverse to the stacking direction. The membrane stack further has a height direction extending parallel to the stacking direction, a longitudinal direction extending perpendicular to the height direction, and a transverse direction extending perpendicular to the height direction and the longitudinal direction. The four stack surfaces form an intake air inlet and an intake air outlet oriented opposite and / or spaced apart from each other in the longitudinal direction, and an exhaust air inlet and an exhaust air outlet oriented opposite and / or spaced apart from each other in the transverse direction. The membrane stack has a plurality of membranes that are permeable to moisture, i.e., water and / or water vapor, and impermeable to air, that are continuous in the stacking direction, and that separate, within the membrane stack, an air intake path connecting the air intake inlet to the air intake outlet from an exhaust path connecting the exhaust inlet to the exhaust outlet.

[0003] For efficient humidification, relatively thin membranes that are closely connected in the stacking direction may be used to achieve a compact structural configuration of the air humidifier. In this case, the membranes may be pressed against each other in the stacking direction. For example, during operation of the air humidifier, a higher pressure is generated in the intake air flow than in the exhaust air flow. This causes the membrane to be pressed outward in the intake air passage toward the exhaust air passage, reducing the cross-sectional area through which the exhaust air passage can pass, which increases the flow resistance to the exhaust air. This impairs the function of the air humidifier.

[0004] The problem addressed by the present invention is to provide an improved embodiment or at least one alternative embodiment of a membrane stack of the above-mentioned type or an air humidifier comprising this membrane stack, which is superior in particular in terms of improved functional safety and / or low flow resistance when passing through the membrane stack along the air supply path and / or the air exhaust path.

[0005] This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0006] The present invention is based on the general idea that the membrane stack comprises a spacer that holds each two directly adjacent membranes defining an exhaust path at a distance within the exhaust path. This prevents the membranes from coming into contact with each other within the exhaust path in the event of overpressure in the supply path. This maintains or guarantees a predetermined cross-sectional area through which the exhaust path can flow, and therefore the membrane stack according to the present invention is superior in terms of low flow resistance.

[0007] Specifically, it is proposed that the film stack has a plurality of spacers, each arranged in one exhaust channel between two immediately adjacent films in the stacking direction. Each spacer is thus assigned two films in contact with it and an exhaust channel defined by both films in the stacking direction. As a result, both films in contact with each spacer are spaced apart in the stacking direction by the spacer within the exhaust channel. The exhaust channel assigned to a spacer is the exhaust channel defined in the stacking direction by both films in contact with the spacer or held apart by the spacer. The spacers are made of a different material than the films. The spacers may be made of, for example, a relatively stable plastic and may be distinguished by a correspondingly high degree of dimensional stability. In any case, the spacers are significantly more dimensionally stable than thin films.

[0008] In one embodiment, it may be specified that each spacer has a tapered portion, in particular a reduced thickness portion, in the height direction between the exhaust inlet and the exhaust outlet. Preferably, the tapered portion of each of two spacers that are directly adjacent in the stacking direction forms and / or defines each air supply path. In other words, the tapered portion of each of two spacers that are directly adjacent in the stacking direction allows the membrane stack to flow along each air supply path in the longitudinal direction. The tapered portion of the spacer has the advantage that less space is required in the height direction or stacking direction for the entire membrane stack.

[0009] In another embodiment, it may be specified that each spacer is configured to be permeable and / or flow-through for the exhaust flow in the transverse direction at the exhaust inlet and / or exhaust outlet, so that the exhaust flow can particularly easily flow into the respective exhaust path through the spacer at the exhaust inlet and / or out of the respective exhaust path through the spacer at the exhaust outlet.

[0010] Preferably, the permeability or flowability of the spacer at the exhaust inlet or outlet can be achieved by having, according to an advantageous embodiment, a plurality of inlet passages at the exhaust inlet, arranged side by side in the longitudinal direction, connecting the exhaust inlet to each of the exhaust paths. Additionally or alternatively, a plurality of outlet passages at the exhaust outlet, arranged side by side in the longitudinal direction, connecting the exhaust outlet to each of the exhaust paths. The inlet or outlet passages significantly simplify the supply of exhaust gas to or the discharge of exhaust gas from each of the exhaust paths located between the membranes in contact with the spacer. Furthermore, the inlet or outlet passages formed in the spacer can ensure a predetermined cross-sectional area for flow at the inlet or outlet of each of the exhaust paths.

[0011] According to another advantageous embodiment, each spacer in each exhaust path may have a plurality of ribs extending transversely along each exhaust path and spaced apart longitudinally. The ribs are configured elongated and particularly straight, and thus have a rib longitudinal direction oriented substantially parallel to the transverse direction. The ribs space the membranes contacting the spacers. For this reason, the ribs contact the membranes. Furthermore, the exhaust flow can easily flow around the ribs in the exhaust path, creating only slight flow resistance. Furthermore, the correspondingly narrow rib arrangement provides good membrane support.

[0012] In this specification, "configuration" is equivalent to "design" and / or "adjustment," and therefore the expression "configured to" is synonymous with the expressions "designed to" and / or "adjusted to."

[0013] According to an advantageous embodiment, the ribs may have a plurality of rib sections that are continuous in the transverse direction and offset from one another in the longitudinal direction. In other words, each rib does not extend consistently across the entire exhaust path in the transverse direction, but is divided into a plurality of continuous rib sections that are offset from one another in the longitudinal direction. This ensures a certain degree of longitudinal mixing and homogenization of the exhaust flow. The fact that the ribs do not extend consistently in the transverse direction can further improve water transport through the membranes of the membrane stack, since the membranes are correspondingly less covered by the ribs.

[0014] In another embodiment, each spacer in each exhaust channel may have a plate extending through each exhaust channel in the longitudinal and transverse directions, with ribs projecting from both sides of the plate in the stacking direction. This allows the exhaust flow guided through each exhaust channel to be divided into two partial flows, one flowing between the plate and one membrane on one side of the plate, while the other flowing between the plate and the other membrane on the other side of the plate. This allows the exhaust channel assigned to each spacer to improve moisture transmission to both intervening supply air channels.

[0015] In another embodiment, each spacer may be configured to be impermeable to air in the stacking direction. This ensures that both membranes defining each exhaust channel are uniformly circulated by the exhaust air, thereby assisting moisture transmission. The spacers may be configured to be impermeable to air in the stacking direction, in particular by the aforementioned plates. For this purpose, in particular, the plates of the spacer may extend across the entire exhaust channel assigned to the spacer in the transverse and longitudinal directions.

[0016] Alternatively, each spacer can be designed to be air permeable in the stacking direction, in which case the ribs can be consistent in the transverse direction and adjacent ribs in the longitudinal direction can optionally be connected to each other by webs, which stabilize the spacer.

[0017] In an advantageous embodiment, it may be specified that each spacer has an inlet region adjacent to the exhaust inlet, and in this inlet region, both membranes in contact with each spacer are fixed to each spacer. The above-mentioned inlet passages may be located in the inlet region. Additionally or alternatively, each spacer may have an outlet region adjacent to the exhaust outlet, and in this outlet region, both membranes in contact with each spacer are fixed to each spacer. The above-mentioned outlet passages may be located in the outlet region. This results in a simplified structure for the film stack. For example, the spacers may be provided with corresponding membranes, thereby forming an intermediate product, which can then be stacked in the stacking direction, thereby forming the film stack.

[0018] Advantageously, both membranes in contact with the respective spacers can be fixed to the respective spacers by material connection, in particular by adhesive or welding. This allows the membranes to be fixed to the respective spacers particularly easily, even in mass production. It is noteworthy that in this case, the membranes are fixed to the spacers with the surface facing the respective exhaust passage, so that the overpressure in the adjacent intake passage presses the membranes toward the spacers, so that only compressive and shear loads are applied to the fixing parts in the stacking direction, but not tensile loads. This is particularly advantageous for membranes that are sensitive to tension.

[0019] According to another embodiment, each spacer has a step in the inlet and / or outlet region for both membranes contacting this inlet and / or outlet region, on which each membrane can be lowered and fixed to the spacer. By lowering or submerging the membranes onto the spacers, the spacers with the membranes, i.e., the intermediate products described above, can be simply stacked in the stacking direction to form a membrane stack.

[0020] It is particularly advantageous if successive spacers in the stacking direction are in contact with and / or fixed to one another outside the membranes in the inlet and / or outlet regions. This simplifies the construction of the membrane stack. In particular, it improves the fixation of adjacent spacers to one another. It is further advantageous that, even if the spacers are distorted or deformed due to the occurrence of loads during operation of the air humidifier, this leaves the (sensitive) membranes at least largely unaffected.

[0021] Advantageously, adjacent spacers in the stacking direction can be fixed to each other in the inlet and / or outlet regions outside the membrane in a material-bonded manner, in particular by adhesive. This fixing technique is particularly easy to implement in mass production. To improve the quality of the adhesive bond, the spacers can have distance elements in the inlet and / or outlet regions, preferably only on one side in the stacking direction, that contact the inlet or outlet regions of adjacent spacers through the adhesive layer. This ensures a consistent thickness for the adhesive layer.

[0022] It is particularly advantageous if each spacer has a rounded inlet or inlet edge at its supply air inlet, which is configured to supply the supply air flow to both supply air channels located on either side of the spacer in the stacking direction. Additionally or alternatively, each spacer may have a rounded outlet or outlet edge at its supply air outlet, which is configured to direct the supply air flow from both supply air channels located on either side of the spacer in the stacking direction. In this way, the supply air flows at the inlets and outlets of both supply air channels located on either side of the exhaust channel assigned to each spacer can be configured to form as few vortices as possible and, as a result, to generate as little flow resistance as possible.

[0023] In another embodiment, each spacer may have at least one support element at the air intake inlet, whereby adjacent spacers in the stacking direction are supported in the stacking direction via the support element at the air intake inlet. Additionally or alternatively, each spacer may have at least one support element at the air intake outlet, whereby adjacent spacers in the stacking direction are supported in the stacking direction via the support element at the air intake outlet. By supporting the stacked spacers at the air intake inlet and / or the air intake outlet, significant stabilization of the membrane stack is achieved. Furthermore, the at least one support element at the air intake inlet and / or the air intake outlet of each spacer eliminates the need for spacers in each air intake path, thereby providing the advantage of a structurally simple membrane stack. Furthermore, the at least one support element at the air intake inlet and / or the air intake outlet may be located outside the membranes arranged on each spacer. This has the advantage that no cutouts need to be made in the membranes for attachment to the spacers, thereby significantly reducing the structural effort.

[0024] Advantageously, the spacers are symmetrically configured in the transverse direction, so that the exhaust inlet and the exhaust outlet have the same structure. Additionally or alternatively, the spacers may be symmetrically configured in the longitudinal direction, so that the air inlet and the air outlet have the same structure. Additionally or alternatively, the spacers may be symmetrically configured in the stacking direction or height direction, so that the spacers have the same structure in this respect. This measure can prevent mix-ups during assembly, respectively.

[0025] The air humidifier according to the invention may be assigned to a fuel cell and used to humidify the dry intake air flow of the fuel cell with the humid exhaust air flow of the fuel cell. For this purpose, the air humidifier has a housing with an intake air inlet port, an intake air outlet port, an exhaust air inlet port, and an exhaust air outlet port. A membrane stack of the above-described form is arranged in the housing. Advantageously, when the membrane stack is inserted into the housing, the intake air inlet port is connected to the intake air inlet, the intake air outlet port is connected to the intake air outlet, the exhaust air inlet port is connected to the exhaust inlet, and the exhaust air outlet port is connected to the exhaust outlet.

[0026] Further important features and advantages of the invention emerge from the dependent claims, the drawings and the corresponding description of the drawings based on the drawings.

[0027] Naturally, the features mentioned above and those further described below can be used not only in the combinations mentioned respectively, but also in other combinations or alone, without departing from the scope of the invention. The separately named components mentioned above and further described below of a superordinate unit, e.g., mechanism, device or assembly, may form separate components or elements of the unit in question, or may be integral regions or sections of the unit, even if shown differently in the drawings.

[0028] Preferred embodiments of the present invention are illustrated in the drawings and will be described in detail in the following description, wherein like reference numerals refer to identical or similar or functionally identical elements. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a schematic isometric view of an air humidifier. [Figure 2] FIG. 1 is a schematic isometric view of a film stack. [Figure 3] FIG. 1 is a schematic isometric view of a section of a film stack. [Figure 4] FIG. 2 is a schematic cross-sectional view of a film stack at an exhaust inlet. [Figure 5] FIG. 1 is a schematic longitudinal cross-sectional view of a membrane stack at an air intake inlet. [Figure 6] FIG. 2 is a schematic enlarged cross-sectional view of the film stack at the exhaust inlet. [Figure 7] FIG. 1 is a schematic partial isometric view of one spacer. [Figure 8] FIG. 1 is a schematic partial isometric view of two spacers next to each other. [Figure 9] FIG. 9 is a schematic enlarged view of the isometric view as shown in FIG. 8. [Figure 10] FIG. 10 is a schematic isometric view as shown in FIG. 9 of only one spacer. [Figure 11] FIG. 10 is a further schematic isometric view of the spacer from another direction.

[0030] The air humidifier 1 shown in FIG. 1 is used in a fuel cell (not shown) to humidify the fuel cell's intake air stream 2 with the fuel cell's exhaust air stream 3. The intake air stream 2 is relatively dry upstream of the air humidifier 1 and relatively humid downstream of the air humidifier 1, so that the exiting humidified intake air stream 2 has a higher humidity than the incoming dry intake air stream 2. The exhaust air stream 3 is relatively humid upstream of the air humidifier 1 and relatively dry downstream of the air humidifier 1, so that the exiting dehumidified exhaust air stream 3 has a lower humidity than the incoming humid exhaust air stream 3. The air humidifier 1 has a housing 4 having an intake air inlet port 5, an intake air outlet port 6, an exhaust air inlet port 7, and an exhaust air outlet port 8. A rectangular parallelepiped-shaped membrane stack 9, as shown in FIG. 2, is disposed within the housing 4. The membrane stack 9 has a stacking direction S and four stack surfaces 10 transverse to the stacking direction S. Furthermore, the film stack 9 has a height direction Z extending parallel to the stacking direction S, a longitudinal direction X extending perpendicular to the height direction Z, and a lateral direction Y extending perpendicular to the height direction Z and perpendicular to the longitudinal direction X. The four stack surfaces 10 form an air intake inlet ZE and an air intake outlet ZA facing opposite each other in the longitudinal direction X, and an exhaust inlet AE and an exhaust outlet AA facing opposite each other in the lateral direction Y. In the assembled state, i.e., when the film stack 9 is inserted into the housing 4, the air intake inlet port 5 provided in the housing 4 is connected to the air intake inlet ZE, the air intake outlet port 6 provided in the housing 4 is connected to the air intake outlet ZA, the exhaust inlet port 7 provided in the housing 4 is connected to the exhaust inlet AE, and the exhaust outlet port 8 provided in the housing 4 is connected to the exhaust outlet AA.

[0031] The membrane stack 9 further comprises a plurality of membranes 11, which can be seen in FIGS. 3 to 11. These membranes 11 are made of a material that is permeable to moisture, particularly liquid and / or vapor water, but substantially impermeable to air. The membranes 11 are continuous in the stacking direction S and separate the air supply paths ZP from the air exhaust paths AP within the membrane stack 9. The air supply paths ZP can be seen in FIGS. 4 to 6 and connect the air supply inlet ZE to the air supply outlet ZA. The air exhaust paths AP can also be seen in FIGS. 4 to 6 and connect the air exhaust inlet AE to the air exhaust outlet AA.

[0032] 3 to 11, the film stack 9 has a plurality of spacers 12, and these spacers 12 are arranged in one exhaust route AP between two films 11 that are directly continuous in the stacking direction S. In this case, the spacers 12 are arranged between two adjacent films 11 so that both films 11 are in contact with their respective spacers 12 and are spaced apart from each other in the stacking direction S within the exhaust route AP in which the spacers 12 are arranged. In other words, the spacers 12 prevent the films 11 that are adjacent to each other in the stacking direction S and that define one exhaust route AP between them from coming into contact with each other within the exhaust route AP.

[0033] 4, 6, 7 and 8, each spacer 12 has a tapered portion, in particular a reduced thickness, in the height direction Z between the exhaust inlet AE and the exhaust outlet AA. The tapered portion of each of two spacers 12 that are directly adjacent to each other in the stacking direction S forms and / or defines a respective air supply path ZP. In other words, the tapering of each of two spacers 12 that are directly adjacent to each other in the stacking direction S allows the membrane stack 9 to flow along the respective air supply path ZP in the longitudinal direction X. The tapered portions of the spacers 12 have the advantage that less space is required in the height direction Z or the stacking direction S for the entire membrane stack 9.

[0034] Each spacer 12 is configured to be permeable and / or passable for the exhaust flow 3 at the exhaust inlet AE and the exhaust outlet AA in the transverse direction Y. This is achieved in the illustrated example in that each spacer 12 shown in FIGS. 3, 4, 6, 8 to 10 has a plurality of inlet passages 13 at the exhaust inlet AE, which are arranged side by side in the longitudinal direction X and connect the exhaust inlet AE to each exhaust path AP. Similarly, each spacer 12 may have a plurality of outlet passages 14 at the exhaust outlet AA shown in FIG. 7, which are arranged side by side in the longitudinal direction X and connect the exhaust outlet AA to each exhaust path AP. According to FIGS. 5 to 10, each spacer 12 in each exhaust path AP may have a plurality of ribs 15, which are linear and elongated, extend along each exhaust path AP in the transverse direction Y, and are spaced apart from each other in the longitudinal direction X. The membrane 11 assigned to each spacer 12 contacts a rib 15 along each exhaust path AP in the stacking direction S. As can be seen in particular in FIG. 8 , the rib 15 may each have a plurality of rib segments 16 that are continuous in the transverse direction Y and are offset from one another in the longitudinal direction X. In other words, each rib 15 does not extend consistently through the entire exhaust path AP in the transverse direction Y, but is divided into a plurality of continuous rib segments 16 that are offset from one another in the longitudinal direction X. The lack of a continuous rib in the transverse direction Y can improve water transport through the membranes 11 of the membrane stack 9, since the membranes 11 are correspondingly less covered by the ribs 15. The spacer 12 in each exhaust path AP has a plate 17, which can be seen in FIGS. 4 to 8 . In this case, the plate 17 extends through each exhaust path AP in the longitudinal direction X and the transverse direction Y. The ribs 15 protrude from both sides of the plate 17 in the stacking direction S. Each spacer 12 may advantageously be configured to be impermeable to air in the stacking direction S.This can be achieved in particular by means of a plate 17, which for this purpose is dimensioned to extend over the entire exhaust path AP or the entire film stack 9 in the longitudinal direction X and the lateral direction Y, respectively.

[0035] According to FIGS. 4 and 6, each spacer 12 may have an inlet region 18 adjacent to the exhaust gas inlet AE, in particular through which the aforementioned inlet passages 13 extend. In this inlet region 18, both membranes 11 in contact with each spacer 12 may be fixed to the respective spacer 12. A material-bonding fastening, in particular an adhesive fastening or welding fastening, is preferred. In FIG. 6, the adhesive regions 19 are indicated by curly brackets for two membranes 11 located on two adjacent spacers 12, facing each other and forming an intake air path ZP between them. Correspondingly, according to FIG. 7, the membranes 11 may also be fixed to each spacer 12 in an outlet region 20 adjacent to the exhaust gas outlet AA, in particular by a material-bonding connection thereto, preferably by adhesive bonding thereto. In the outlet region 20, the outlet passages 14 may be located. Furthermore, each spacer 12 may have a step 21 for both membranes 11 in the inlet region 18 shown in Figures 6 and 11 and in the outlet region 20 shown in Figure 7, respectively, on which the membranes 11 are lowered and placed and fixed to the spacer 12. In particular, adhesion is achieved between the membranes 11 and the spacer 12 within the area of ​​the step 21.

[0036] According to Figures 4 and 6, consecutive spacers 12 in the stacking direction S may be in contact with each other and / or fixed to each other outside the membrane 11 in the inflow region 18. This has the advantage that if the spacers 12 are distorted or deformed due to the occurrence of loads during operation of the air humidifier 1, the (sensitive) membrane 11 remains at least largely unaffected. In Figure 6, the application regions 22 and / or fixing regions 23, where adjacent spacers 12 are in contact with each other and / or fixed to each other, are indicated by curly brackets. The fixing of the two spacers 12 in contact with each other may preferably be effected materially, in particular by means of an adhesive.

[0037] 5 and 8 to 10, each spacer 12 may have a rounded inflow edge 24 at the air intake inlet ZE, which is configured to advantageously deflect or redirect the air intake flow 2 and guide it with low flow resistance to both air intake paths ZP located on both sides of each spacer 12 in the stacking direction S. Correspondingly, each spacer 12 may have a rounded outflow edge (not shown) at the air intake outlet ZA, which is configured to advantageously guide the air intake flow 2 from both air intake paths ZP located on both sides of each spacer 12 in the stacking direction S. In particular, the inflow edge 24 and the outflow edge may be configured with the same structure.

[0038] 3, 5 and 8, each spacer 12 may have at least one support element 25 at the air intake inlet ZE. This support element 25 is configured so that adjacent spacers 12 in the stacking direction S can support each other in the stacking direction S at the air intake inlet ZE via the support element 25. In this case, in the preferred embodiment shown, the support element 25 of one spacer 12 is supported by the support element 25 of the other spacer 12. In principle, embodiments are also possible in which the support element 25 of one spacer 12 is directly supported by the other spacer 12, and vice versa. Advantageously, a similar configuration may also be realized at the air intake outlet ZA, whereby each spacer 12 has at least one support element (not shown) at the air intake outlet ZA, where again the support element is configured so that adjacent spacers 12 in the stacking direction S are supported by the support element 25 at the air intake outlet ZA in the stacking direction S. In principle, the support elements at the intake air outlets ZA can be configured identically to the support elements 25 at the intake air inlets ZE. At least one support element 25 of each spacer 12 at the intake air inlets ZE and / or at least one support element at the intake air outlets ZA offers the advantage that no spacers are required in each intake air path ZP, thereby enabling a structurally simple membrane stack 9 to be realized. Furthermore, according to FIGS. 3 and 5, the at least one support element 25 at the intake air inlets ZE and the at least one support element at the intake air outlets ZA can be located outside the membranes 11 arranged on each spacer 12. This has the advantage that no cutouts need to be made in the membranes 11 for attachment to the spacers 12, which significantly reduces the structural effort.

[0039] According to FIG. 6, during operation of the air humidifier 1, a pressing force 26, indicated in FIG. 6 by a double-headed arrow extending parallel to the stacking direction S, is generated in the supply air path ZP. This pressing force 26 arises because, during operation of the air humidifier 1, a greater pressure is typically generated in the supply air flow 2 than in the exhaust air flow 3. Correspondingly, an overpressure is generated in the supply air path ZP relative to the adjacent exhaust air path AP. The resulting pressing force 26 drives both membranes 11 defining each supply air path ZP in the stacking direction S toward the respective adjacent exhaust air path AP. However, the height of each exhaust air path AP, measured in the height direction Z, is determined by the spacers 12 extending within this exhaust air path AP. As a result, the membranes 11, which are loaded by the overpressure in each supply air path ZP, can be supported by the respective spacers 12 within the respective adjacent exhaust air path AP. The overpressure in each air supply channel ZP also subjects the fastening area 19 to a pressure load in the stacking direction S, which does not pose a problem for the fastening between the membrane 11 and the spacer 12 . [Explanation of symbols]

[0040] 1 air humidifier 2. Intake air flow 3 Exhaust flow 4. Housing 5 Air intake port 6 Air intake and outlet ports 7 Exhaust inlet port 8 exhaust outlet ports 9 Membrane laminate 10 Laminate surface 11 membrane 12 spacer 13 Inflow passage 14 Outflow passage 15 Ribs 16 Rib Section 17 Plate 18 Inflow area 19 Fixed area 20 Outflow area 21 Step section 22 Assignment Area 23 Fixed area 24 Inflow edge 25 Supporting Elements 26 Pressing force S Stacking direction X Longitudinal direction Y horizontal direction Z height direction ZE Air intake ZA Air intake outlet AE exhaust inlet AA exhaust outlet ZP air supply route AP exhaust route

Claims

1. A membrane stack (9) for a fuel cell air humidifier (1) for humidifying a dry fuel cell inlet air stream (2) with a humid fuel cell exhaust air stream (3), comprising: The film stack (9) is configured in a rectangular parallelepiped shape and has a stacking direction (S) and four stack faces (10) transverse to the stacking direction (S), The film stack (9) has a height direction (Z) extending parallel to the stacking direction (S), a longitudinal direction (X) extending perpendicular to the height direction (Z), and a lateral direction (Y) extending perpendicular to the height direction (Z) and perpendicular to the longitudinal direction (X), The four laminate faces (10) form air intake inlets (ZE) and air intake outlets (ZA) that are directed opposite and / or spaced apart from one another in the longitudinal direction (X) and exhaust inlets (AE) and exhaust outlets (AA) that are directed opposite and / or spaced apart from one another in the transverse direction (Y), The membrane stack (9) comprises a plurality of membranes (11), which are permeable to moisture and impermeable to air, are continuous in the stacking direction (S), and each membrane (11) separates, within the membrane stack (9), an air supply path (ZP) connecting the air supply inlet (ZE) to the air supply outlet (ZA) from an exhaust path (AP) connecting the exhaust inlet (AE) to the exhaust outlet (AA). In the film stack (9), The membrane stack (9) has a plurality of spacers (12), each spacer (12) being arranged in one of the exhaust paths (AP) between two membranes (11) that are directly adjacent to each other in the stacking direction (S).

2. Each of the spacers (12) has a tapered portion, in particular a reduced thickness portion, in a height direction (Z) between the exhaust inlet (AE) and the exhaust outlet (AA), The tapered portions of each of two spacers (12) that are directly adjacent to each other in the stacking direction (S) form and / or define the respective air supply paths (ZP).

2. The membrane stack (9) according to claim 1, characterized in that it comprises:

3. 3. The membrane stack (9) according to claim 1 or 2, characterized in that each spacer (12) is configured to be permeable and / or passable for the exhaust flow (3) in the transverse direction (Y) at the exhaust inlet (AE) and / or the exhaust outlet (AA).

4. Each of the spacers (12) has, at the exhaust inlet (AE), a plurality of inlet passages (13) arranged side by side in the longitudinal direction (X) and connecting the exhaust inlet (AE) to each of the exhaust paths (AP); and / or Each of the spacers (12) has a plurality of outlet passages (14) arranged side by side in the longitudinal direction (X) at the exhaust outlet (AA), and the plurality of outlet passages (14) connect the exhaust outlet (AA) to each of the exhaust paths (AP).

4. The membrane stack (9) according to claim 1, characterized in that it is

5. 5. The membrane stack (9) according to claim 1, wherein each of the spacers (12) in each of the exhaust paths (AP) has a plurality of ribs (15) extending along each of the exhaust paths (AP) in the transverse direction (Y) and spaced apart from one another in the longitudinal direction (X).

6. 6. The membrane stack (9) according to claim 5, characterized in that the rib (15) has a plurality of rib sections (16) that are continuous in the transverse direction (Y) and arranged offset from one another in the longitudinal direction (X).

7. 7. The membrane stack (9) according to claim 5 or 6, characterized in that each of the spacers (12) in each of the exhaust paths (AP) has a plate (17) extending through each of the exhaust paths (AP) in the longitudinal direction (X) and the transverse direction (Y), and the ribs (15) protruding from both sides of the plate (17) in the stacking direction (S).

8. 8. Membrane stack (9) according to any one of claims 1 to 7, characterized in that each spacer (12) is configured impermeable to air in the stacking direction (S).

9. Each of the spacers (12) has an inlet area (18) adjacent to the exhaust inlet (AE), in which both of the membranes (11) in contact with each of the spacers (12) are fixed to each of the spacers (12); and / or Each of the spacers (12) has an outflow area (20) adjacent to the exhaust outlet (AA), and in the outflow area (20), both of the membranes (11) in contact with each of the spacers (12) are fixed to each of the spacers (12).

9. The membrane stack (9) according to any one of claims 1 to 8, characterized in that it comprises:

10. Each of the spacers (12) has a step (21) in the inlet area (18) for each of the membranes (11) that contact the inlet area (18), on which each of the membranes (11) is lowered and placed and fixed to the spacer (12); and / or Each of the spacers (12) has a step (21) in the outflow area (20) for each of the membranes (11) that contact the outflow area (20), and each of the membranes (11) is lowered onto the step (21) and fixed to the spacer (12).

10. Membrane stack (9) according to claim 9, characterized in that

11. 11. The membrane stack (9) according to claim 9 or 10, characterized in that the spacers (12) that are consecutive in the stacking direction (S) are in contact with each other and / or fixed to each other outside the membranes (11) in the inlet region (18) and / or the outlet region (20).

12. 12. The membrane stack (9) according to claim 11, characterized in that the spacers (12) that are consecutive in the stacking direction (S) are fixed to one another in a material-bonded manner, in particular by adhesive, outside the membranes (11) in the inlet region (18) and / or the outlet region (20).

13. Each of the spacers (12) has a rounded inlet edge (24) at the air supply inlet (ZE), which is configured to supply the air supply flow (2) to both of the air supply paths (ZP) located on either side of each of the spacers (12) in the stacking direction (S); and / or Each of the spacers (12) has a rounded outflow edge at the air supply outlet (ZA), and the outflow edge is configured to direct the air supply flow (2) from both of the air supply paths (ZP) located on both sides of each of the spacers (12) in the stacking direction (S).

13. The membrane stack (9) according to any one of claims 1 to 12, characterized in that it is

14. Each of the spacers (12) has at least one support element (25) at the air intake inlet (ZE), so that adjacent spacers (12) in the stacking direction (S) are supported by the support element (25) at the air intake inlet (ZE) in the stacking direction (S), and / or Each of the spacers (12) has at least one support element (25) at the air supply outlet (ZA), whereby adjacent spacers (12) in the stacking direction (S) are supported by the support element (25) at the air supply outlet (ZA) in the stacking direction (S).

14. The membrane stack (9) according to any one of claims 1 to 13, characterized in that it is

15. An air humidifier (1) for a fuel cell for humidifying a dry inlet air flow (2) of said fuel cell with a humid exhaust air flow (3) of said fuel cell, comprising: a housing (4) having an intake air inlet port (5), an intake air outlet port (6), an exhaust air inlet port (7), and an exhaust air outlet port (8); A membrane stack (9) according to any one of claims 1 to 14, arranged in the housing (4); An air humidifier (1).

Images